Multiple position door latch mechanism

ABSTRACT

A three-position, sliding latch mechanism for an appliance door such as an oven door. The mechanism includes a latch handle and a hidden latching bolt for swinging out and engaging the door. The first position of the latch mechanism is an unlocked position, and the second position is a locked position. The third position is also a locked position, although the latching bolt remains stationary in this locked position as the latch handle is moved between the second and third positions. There are separate interlock switch means that are operable in either the first (unlocked) or the second and third (locked) positions, whereby different oven operations may be performed as a function of the various positions of the latch handle so as to simplify the control circuitry and components.

14 1 Aug. 7, 1973 Fowler et al.

MULTIPLE POSITION DOOR LATCH MECHANISM 3,540,767 11/1970 Siegel 126/197Primary Examiner-Carroll B. Dority, Jr.

[75] Inventors: Roland V. Fowler; James A. White;

v Dvid C. Cross a" of Louisville y Attorney Richard L. Caslin et al.

[73] Assignee: General Electric Company, [57] ABSTRACT Lousvluei Y- Athree-position, sliding latch mechanism for an appli- 22 Filed; May 231972 ance door such as an oven door. The mechanism includes a latchhandle and a hidden latching bolt for [2'1] Appl- 256,093 swinging outand engaging the door. The first position of the latch mechanism is anunlocked position, and the 52 us. 01 126/197, 219/413, 292/113, SecondPosition is a locked Pvsifion. The third Position 292/1316. 69 is also alocked position, although the latching bolt re- 51 .1111. Cl. F23m 7/00,F241; 15/04 mains Stationary in this locked Position as the latch 58Field of Search 292/97, 196, DIG. 69, handle is moved between the Secondand third P s 292 113; 12 197; 2 9 4 3 tions. There are separateinterlock switch means that are operable in either the first (unlocked)or the sec- [5 References cited and and third (locked) positions,whereby different UNITED STATES PATENTS oven operations may be performedas a function of the I various positions of thev latch handle'so as tosimplify I the control circuitry and components.

3,367,697 2/1968 Fox 292/113 13 Claims, 8 Drawing Figures 7 1 5 5O '5' 4(a Q6 Q5 7O 7\ I ,1 a: I I (0e 4. r

113 y i H7 74 I 107 88 v 98 4 119 I2 I as Q ris 101 13 S9 82 g, 84- looI 3 1G3 1 9 S's f 05 155 12 7e =l 14s 61 I 41 M PAIENIEBAUB mu v3,750,543

sum 3 OF 4 Has r Q MULTIPLE POSITION DOOR LATCH MECHANISM BACKGROUND OFTHE INVENTION This invention was specially designed for a door latchingsystem for a microwave oven that is provided with the added convenienceof a pyrolytic self-cleaning oven cycle, but clearly the invention isnot limited to a maximum of three positions. It is imperative that amicrowave oven have its oven door latched during its opetation so as toprevent the leakage of microwave energy from the oven cooking cavity,since such radiation that are formed as metal sheathed resistanceheating elementsthat are sold under .the registered trademark ofCALROD-heating units. For such conventional cooking, the door latchwould be set in its first (,unlocked)position. H I

The oven'is also furnished with a microwave generator and powersupplythat may fu rnish microw'ave energy in one of two frequency bands of 915mI-Iz or x 2,450 mI-Iz for increased speed of cooking. To'accomplishthis function, the oven door would be locked, with the latch mechanismset in its second (locked) position.

It is possible to combine the action of the two heating means so as tohave both radiant energy and microwave energy furnished to the ovencavity simultaneously I while in this second (locked) position.

When-the oven is to be cleaned of the food soils and grease spattersthat accumulate on the inner surfaces of the oven liner and inner'doorliner, the door la'tch would be moved to its third (locked) position.Then the radiant heating elements would. be energized to raise the oventemperature to about 900F. for a'sufficient length of time to degradethe food soils with the production of corresponding gaseous degradationproducts that are returned to the kitchen atmosphere .as harmless gases.

It has been found expedient to provide separate door interlock switchesand circuits for operation during the second and third (locked)positions of the door latch fordiscriminating between the microwavecooling operation and the pyrolytic self-cleaning oven cycle so as tosimplify the control circuits and reduce the cost of electricalcomponents.

S U MMARY OF "THE INVENTION A multiple-position,sliding latch mechanismcomprising a base plate and a latch handle that ispivotally connected tothe base plate adjacent the rear thereof so as to'flatten the arc of thepath of movement of the outermost portion of the latch handle. The latchmechanism includes a latching bolt that is connected to both the baseplate and the latch handle through a latch lever. There are two lockedpositions of the latch mechanism between which the latching bolt remainssubstantially stationary. Separate interlocking switch means cooperatewith the latch mechanism in either the first (unlocked) or thesecond andthird (locked) positions to set up independent controlcircuits.

The. principle object of the present invention isto provide amultiple-position,sliding latch mechanism having a first (unlocked)position, a second (locked) position and a third (locked) position, andlocking means for the latching mechanism to restrict the forwardmovement from the second (locked)position to the third (locked) positionunder certain circumstances, as well as to prevent the return movementfrom the third (locked) position toward the second (locked) position orthe first (unlocked)-position when the oven air temperature is aboveabout 600 F.

A further object of the present invention istoprovide amultiple-position, door latch mechanism with a special' latch handlethat has an outermost end portion with a flattened are as its path ofmovement'so as not to constitute an obstruction in its intermediateposition.

A further object of the present invention is to provide athree-position, door latch mechanism with separate interlock switchmeans operablein the'first (unlocked) or the second and third (locked)positions so that the position of the latch mechanism discriminatesundifferentiates between the various operating cycles'that the latchmechanism is'to initiate andcontrol. v

BRIEF DESCRIPTION OF THE DRAWINGS .Ourinvention will be betterunderstoodzfrom thefollowing description taken inconjunction with theaccompanying drawings and its scopewill-bepointediout in the appendedclaims.

FIG..I is a right side elevational view of a freestanding electric rangewith amicrowave oven that -it equipped with a multiple-position, ovendoor latch mechanism embodying the present'invention.'FIGQZis afragmentaryplan view onan enlarged scale 'takenon the line 2-2 of FIG. 1to show the three-'position'latch mechanism of the present invention in'its'first (:unlatched) position for non-use of the ovenorconventionalcooking within the oven.

FIG. 3 is another plan view of the latchmechanism, similar to that ofFIG. 2, except the handle hasbeen moved to its second (locked) positionfor 'microwave cooking or combined microwave and conventional cooking.

FIG. 4 is another plan view of the latch imechanism showing the latchhandle in itsthird (locked) position fora pyrolyticself-cleaning ovencycle.

FIG. 5 is a fragmentary elevational view of'the locking' means for thedoor latching mechanism taken on the line 5-5 of FIG. 2 showing theposition of thelocking means when the door latchmechanism-isin itsfirst(unlocked) position of FIG. 2.

FIG. 6 is another fragmentary elevational view, similar to that of FIG.5, showing the positionzof the locking means when the door latchmechanism is-in its second (locked) position of FIG. .3.

FIG. 7 is another fragmentaryelevational view,;similar to that of FIG.6, showing the positionof the locking means when the door latchmechanism is in its third (locked) position of FIG. 4.

FIG. 8 is a schematic diagram of boththe powerand control circuitsforthevarious heating systemsof the oven locating the separate interlockswitches for the microwave oven operation and the self-cleaning ovenoperation toemphasizethat these-various cycles are set up by thealternate positions of the door latch mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to a considerationof the drawings and in particular to FIG. 1, there is shown forillustrative purposes a free-standing electric range having a topcooking surface 11 with a plurality of surface heating elements 12, anoven cooking cavity 13 beneath the top cooking surface, a front-openingoven door 14 hinged along its bottom edge 15, and a backsplash 16arranged along the back edge of the cooking surface 11 and including inits front face a control panel with all the manual and visual controlcomponents 17 mounted therein for governing the energization of thevarious heating means of the range. The oven cooking cavity 13 includesthe'two standard electric heating elements; namely, a lower bake element18 arranged along the bottom wall of the box-like oven liner 21, and anupper broil unit 19 which is located adjacent the top wall of the ovenliner. As in conventional electric ovens, there is a layer 23 of thermalinsulation surrounding the walls of the oven liner 21 for retaining theheat generated within the cookingcavity 13. Moreover, the oven door 14is an insulated door construction so as not to allow excessively hightemperatures to exist on the outer surface of the door which might causea safety hazard. The oven door requires a special door sealingarrangement on its inner surface in the vicinity of the door gap withrelation to the front flange of the oven liner 21 in the area marked 25to prevent both microwave leakage during microwave cooking and smoke,odor and thermal leakage during the self-cleaning cycle. Sincethis doorgasketing does not form part ofthe present invention, it has not beenillustrated not described in detail.

The microwave features of the oven will now be described briefly withreference to FIG. 1. Beneath the oven 13 is a compartment 27, which inan ordinary range would be a drawer space, but in this particular range.would be the housing for a magnetron generator 29 in combination with apower supply 32, and blower 34 for cooling the magnetron and powersupply components under operating conditions. These three assemblies aremounted on a pull-out tray 36 which is provided at its front edge with'avertical panel 37 which conforms to the appearance of the oven door 14and serves to close the apparatus compartment 27 and to appear like adrawer structure. In other words, the movable tray 36 serves as thebottom wall of a drawerlike member which is without side walls for readyaccess to the magnetron, power supply and blower. A waveguide 39 risesvertically from the magnetron generator 29 and extends through thebottom wall of the oven liner 21, generally in the center thereof. Anantenna 40 is mounted from the waveguide just above the bottom wall ofthe oven liner 21 for propagating the microwave energy throughout theoven cooking cavity 13. In order to obtain uniform cooking results, amode stirrer or parasitic exciter 42 is assembled adjacent the top wallof the oven liner'generally centered above the antenna 40, and it ismounted on a shaft that extends through the top wall of the oven linerfor connection to a motor and gear drive assembly 44. The stationaryantenna 40 serves to set up a basic TE 1 31 mode which excitescomplementary TE122 modes in the mode stirrer or parasitic exciter 42.There would be a metal rack (not shown) suspended between the side wallsof the oven liner for supporting food to be cooked within the ovencooking cavity 13.

The door latch mechanism of the present invention is indicated by thenumeral in FIG. 1, and it is preferably located within the oven cabinetor range body above the door opening and above the top layer of thermalinsulation 23. As mentioned previously, the use of a door latchmechanism of some kind has been found of primary importance in theoperation of a hightemperature, pyrolytic self-cleaning oven. In such anoven theremay be provided, in addition to the lower bake element 18 andthe upper broil element 19, a third heating element or mullion heater 52as seen in FIG. 1 that is located near the door opening of the ovenliner 21 to encircle the oven liner, or at least part of it, thecompensate for the loss of heat through and around the oven door 14 forobtaining uniform temperature distribution.

Referring particularly to FIGS. 2, 3 and 4, the latch mechanism 50 isshown as comprising a mounting bracket or base plate 54 whichisgenerally of flat sheet metal configuration with an upturned verticalfront flange 55 which is adapted to be fastened against the innersurface of the front door frame 56 of the oven body. The base plate 54has a second upturned vertical flange 58 along the right side edgethereof which is adapted to support a first door interlock switch 60 foruse in the microwave power supply circuits. Another upstanding verticalflange 61 is located along the left side of the base plate 54 and itserves as a mounting means for a second door interlock switch 63 for usein the oven' thermostat circuit in the self-cleaning oven mode. There isanother upstanding vertical flange 65 adjacent the right side of thebase plate, near the front thereof, and this serves as an anchoringmeans for one end of a tension spring 66 that is connected at its otherend 67 to a pivoted cam follower 68. There ,is a latching bolt 70 with afront hook portion 71. This latching bolt is pivotally as well asslidably connected to the base plate 54 by a pivot pin 72. Positioned ontop of the latching bolt 70 is a door sensor bar 74. The presence ofthis door sensor bar overlying the latching-bolt 70 tends to complicatean understanding of the drawings. This door sensor bar 74 is not pivotedon the pin 72 on which the latching bolt 70 is pivoted. There is a fixedpin 76 that is carried by the innermost end of the door sensor bar 74.This pin 76 extends down through they latching bolt and is captured in acam-shaped guide slot 78 formed in the base plate 54. The top of the pin76 is confined in a second cam-shaped slot 80 that is formed in a latchlever 82 that in turn is pivotally mounted to the base plate 54 by meansof a central pivot bolt 84.

Next there is the latch handle 86 that is an elongated bar that ispivoted to the base plate 54 by a sliding bolt 88 that is confined in anelongated slot 89 in the base plate. This slot 89 extends in a directionfrom front to back of the front mounting flange S5 of the base plate. Inaddition, the latch handle 86'is connected to the latch leverby a pivotpin 90 such that movement of the latch handle 86 from right to left inFIG. 2 causes the latch lever 82 to move in a counterclockwise directionsuch that the cam slot 80 exerts a pressure on the pin 76 that extendsthrough both the door sensor bar 74 and the latching bolt 70 causing thesensor bar and the latching bolt as a unit to move in a clockwisedirection generally about the pivot pin 72.

The interrelation between the latching bolt 70 and the door sensor bar74 is the same as is taught in U.S. Pat. No. 3,367,697 of Joseph S. Fox,Sr., which is assignedto the same assignee as is the present invention.A bent-up tab 92 extends upwardly from the left side of the latchingbolt 70 to extend above the door sensor bar 74. An opposing tab 94 isfolded up from the right side of the door sensor bar so that a smalltension spring 96 may be connected between the two tabs 92 and 94 so asto normally retain the door sensor bar 74 in a position where itoverlies the front hook portion 71 of the latching bolt 70, but iscapable ofa small amount of relative movement therefrom, as is best seenin FIG. 3. This door sensor bar 74 also has a hook portion 98 which actsin the event the oven door 14 is not in its fully closed position toengage with the side edge 100 of a slot 101 formed in the front flange55 of the base plate 54. This interengagement would prevent any furthermovement of the latch mechanism into the second or third positions. Inthe event the oven door 14 is in its closed positionflas best seen inFIG. 3, then the edge the locking bolt 70, this bolt will be pulledrearwardly thereby putting a tension force on the oven door 14 causingitto be compressed against its door gasket (not shown.) and form a tightseal.

In comparing the first (unlocked) position of the door latch of FIG. 2,with the second (locked) position ofFlG. 3, it will be seen that in thesecond.(locked) position a side extensionor spur 107 at the rearmost endof the door handle 86 serves to engage a button or switch actuator 109of the door interlock switch 60 so as to close certain microwavecircuits in which this interlock switch is interposed.

This latch mechanism has also been designed to provide a third (locked)position as is illustrated in FIG. 4. When moving through the second(locked) position to v the third (locked) position, the latching bolt 70remains substantially stationary. The latch handle 86 is moved from anintermediate position of FIG. 3 to the extreme left position of FIG. 4.This feat is accomplished mainly by extending the cam slot 80 to theleft sition, and a second detent 121 for use in the third (locked)position. This cam surface 114 cooperates with a pivoted cam follower68, that was mentioned previously. The cam follower is generally in theshape of a bell-crank lever of spaced double thickness that is pivotedto the base plate at its center by a pivot'bolt.

tween the first (unlocked) position and the second (locked) position isabout 65 degrees. The included angle between the second (locked)position and the third (locked) position is about degrees, or a total ofabout 85 degrees from the first (unlocked) position to the third(locked) positiomLooking back to FIG. 3,

there is at the left side of the latch mechanism a reciprocablelockingbar 127 which is of elongated shape that during the final momentsof the lockingactionof at a constant radius thereby allowing the latchlever 82 to pivot around its pivot bolt 84 for 20. Looking at the pin76in FIG. 3, the cam slot is shown with about 215 dwell to the rightthereof which allows the latch handle 86 to be moved to the right towardthe first (unlocked) position without relieving the tension on thelocking bolt 70 and hence the door gasket to prevent the ovendoor 14from opening until the microwave interlock switch 60 is deenergized toshut off the microwave power to the magnetron generator 29 before thedoor sealing gasket relaxes. I

Attention is drawn to the right side edge of the latch lever 82 that isformed with a cam surface 114 having a stop formation 115 for use in thefirst (unlocked) position, a long sweeping slowing rising cam surface117 and a first detent 1 19 for use inthe second (locked) pothat ispivotally. connected at one end to the latch lever 82 by means of apivotpin 129; 1

Turning to the cross sectional elevational view of FIG. 5, there isshown an upstanding bracket member 131 having a small horizontal slottedopening 132 receiving' and supporting the locking bar 127 therethroughin a close fitting relationshipfor guiding the movement-of the lockingbar as the .latchlever' 82 turns when the latch handle 86 is shiftedfrom one of the three positions. This bracket member has a lowerhorizontal base portion 134 which is fastened beneath the base plate 54by means of fastening screws 135. This bracketmember 131 has itsvertical side edges'folded forwardly intoside walls 137 for supportingadjacent the bottom an elongated pivot pin 139 therebetween. Carried bythis pivot pin 139 is a verticallypivoted lock lever 141 as is best seenin FIG. 5. This lock lever 141 has the shape of a bell-crank lever witha-gen'erallyhorizontal arm 142 and a generally vertical arm 143. Thevertical arm 143 of the lock lever 141 is pivotally connected to anarmature 145 of a solenoid 147 by a cotter pin. This solenoid is shownsupported beneath a horizontally disposed top flange 149 of the bracketmember 131 by means of fastening screws 151. There is a spiral spring153 slipped over the armature 145 for normally biasing the armatureoutwardly of the solenoid housing such that the energization of thesolenoid 147 causes the armature to be pulled in for pivoting the locklever 141 in a clockwise direction about its pivot pin 139, as bestvseenin FIG. 5. 1

Notice in FIG. 5 that the locking bar 127 has two elongated slots 155and 157 formed therein. The front slot 155 is provided with a short,downwardly inclined ramp 159 adjacent the front edge thereof. Moreover,there is a cross bar 161 separating the'front slot 155 from the rearslot 157. The horizontal arm 142 of the lock lever 141 has a downwardlyinclined-hook forma-, tion 163. Comparing FIGS. 2 and 5, which is thefirst (unlocked) position of the latch mechanism, the-hook formation 163of the locklever 141 is shown resting on top of the locking bar 127.When the latch handle 86 is moved to the second (locked) position asseen in FIGS. 3 and 6, the locking bar 127 is pulled forward by thelatch lever 82, thereby allowing the lock lever 141 to drop down intothe slot 155 a's'is seen in FIG. 6, thus preventing further movement ofthe latch handle in the forward direction toward the third (locked)position. It should be understood that the action of the lock lever 141in making locking engagement with the cross bar 161 in the'second(locked) position, does not preclude the normal return action of thelatch handle 86 from the second position back to its first (unlocked)posi- 111011.

In order to disconnect the lock lever 141 from the cross bar 161 of thelocking bar 127, so as to be able to shift the latch handle 86 from thesecond (locked) position to the third (locked) position, it is firstnecessary to energize the solenoid 147, thereby causing the armature 145to be activated and drawn into the solenoid, thereby pulling back on thevertical arm 143 of the lock lever 141 and lifting the hook end 163 outof the slot 155. Then the latch handle 86 may be shifted to its thirdposition at which time the solenoid 147 would be de-energized and thelock lever 141 would assume the position shown in H0. 7 due to theaction of the spiral spring 153, thereby causing the switch 148 to closeso as to short out the oven temperature control 182 in the self-cleaningmode. Then it can be seen that the hook portion 163 of the lock lever141 has been allowed to fall behind the cross bar 161 of the locking bar127, and this temporarily prevents manipulation of the latch mechanismin rearward directions. This condition can only be altered when thesolenoid 147 is again energized, thereby lifting the lock lever out ofengagement with the locking bar 127 and enabling the latch handle to bemoved to either, the second or first positions.

Looking at FIGS. 3 and 4, it should be noted that there is a secondinterlock switch 63 mounted on a side extension 172 of the base plate54. This switch has a pivoted spring biased toggle actuator 174 whichoverlies a portion of the locking bar 127., An upstanding finger 176 iscarried at the side of the locking bar for engaging the toggle actuator174 during the movement of the latch handle 86 from the second to thethird position of the latch mechanism to thereby close the switch 63 forsetting up the self-cleaning oven circuit. This toggle actuator 174 hasan internal spring mechanism (not shown) which returns the toggle to itsnormal open position shown in FIG. 2.

7 Now turning to the schematic circuit diagram of FIG. 8, the oven isshown furnished with an electrical service of three-wire Edison sourceof power, nominally of 230 volts, single phase, 60 Hz, A.C., which isusually available in the average residence having adequate wiring. Thisvoltage source is fed to the oven through a threewire cable having apair ofline wires L and L with a voltage of 240 volts therebetween, anda grounded neutral conductor N with half voltage or 120 volts measuredacross any line wire L or L, with the neutral conductor N for supplyingpower to the electrical load of the oven. The conventional electricalload is characterized by three heating elements: a baking element 18, abroiling element 19, and a mullionheater 52. These heating elements 18,19 and 52, are arranged in varying circuits by virtue of an ovenselector switch 180 for setting up different combinations of heatingelements at different voltages to obtain a variety of heating rates. Amanually settable oven thermostat 182 is also available for controllingthe temperature within the oven at preselected temperatures duringbaking operations, and at a separate maximum temperature during broilingand oven cleaning operations. Such an oven thermostat 182 controls ahot-wire relay 184 that is in series with the heating elements 18', 19and 52 for opening and closing the power circuit to the heating elementsas a function of the oven temperature with relation to the temperaturepredetermined or preset by the thermostat 182. g

The oven selector switch 180 is provided with a series of line terminalsL N, L, and L as well as a series of three load terminals K, J and P.This oven switch 180 is provided with a plurality of switch contacts192-200. These switch contacts are labeled with the particular cookingor cleaning operation that is involved when such contacts are closed.For example, during a Baking" or a Time-Baking operation, contacts 192,193, 198 and 199 are closed. During a Broiling operation, contacts 196and 197 are closed. During a Cleaning Cycle," contacts 193, 194, 195,196, 199 and 200 are closed.

The Baking" circuit has the bake element 18 operating at full wattageacrosslines L, and L at 240 volts through a temperature switch 202 whichconnects the selectorswitch 180 with line L while the other end of thebake element 18 is connected to the hot-wire relay 184 and through asmoke eliminator 204 to the other line L During, the Baking" cycle, theother two heating elements 19 and 52 are also energized. They are in aseries circuit connected back through the temperature switch 202 to lineL,, and also connected through the hot-wire relay 184 and smokeeliminator 204 to the line L2. 1

In the Broiling circuit, only the broil element 19 is energized, and itis connected across lines L, and L through the temperature switch 202 aswell as through the hot-wire relay 184 and smoke eliminator 204 to lineL If a component failure should occur during a cooking operationofeither Baking, Time-Baking or Broiling, and the oven temperature were torise above the preset temperature of the oven thermostat 182 and reachan oven temperature of say 580 F., then the temperature switch 202 wouldbe operating to open the circuits therethrough, thereby deenergizing theheating elements 18, 19 and 52 and preventing a runaway temperaturecondition. Thus, this temperature switch 202 serves as anovertemperature limit control when the oven is in any normal cookingoperation. Thus, in the event ofa malfunction of the primary temperaturecontrol, any hazard due to overheating of the oven during the Baking,Broiling and Time-Baking mode of operation is eliminated. Thisparticular temperature switch is described in U.S. Pat. No. 3,656,182 ofPaul R. Staples,

entitled Hydraulic Thermostat With Double Throw Switch Mechanism," whichis assigned to the same assignee as is the present invention.

During a self-cleaning mode of operation, the oven selector switch isnot connected through the temperature switch 202 to line L but insteadis connected to neutralconductor N by means of lead 208. However, thetemperature switch 202 does connect 2 fan motor 210 to line L by meansof lead 211. During the selfcleaning operation, the three heatingelements 18, 19 and 52 are connected in parallel at half voltage acrossline L; and neutral conductor N in order to obtain a heating ratesomewhat lower than the heating rate during normal baking operations.This temperature switch 202 is a single-point thermostat set at about580 F. At

temperatures below about 580 F., this switch is closed to connect a lead213 to the selector switch 180 for normal cooking operations. Attemperatures about 580 F., the temperature switch 202 opensthe circuitto the lead 213 and closes it to the lead 211. As mentionedpreviously,'there is a solenoid 147 for cooperation with the lock lever141 in its cooperation with the locking bar 127. This solenoid isconnected at one side to line L, through leads 213, 215 and 216. in thislead 216 is'a momentary latch-release switch 218 which might be mountedin the backsplash 16. The other side ofthe solenoid is connected by lead220 through switch contacts 221 and 222 of the oven selector'switch 180,and then back to neutral conductor N by way of lead 224. Thus, attemperatures above 580 F., the temperature switch 202 opens a circuit tolead 213, thereby deenergizing the circuit for the solenoid 147 andrendering the door latch mechanism inoperable until the temperature ofthe oven returns to below the critical temperature of about 580-F.During such a high temperature operation, the temperature switch 202 isclosed for establishing a circuit to lead 211 and the cooling fan 210and by means of lead 226 through a thermal fan I switch 228, and thenthrough the second interlock switch 63 and back to neutral conductor Nby means of lead 232 and lead 224.

In order to set up the self-cleaning oven circuit, there are severalpreliminary operations that must be performed first. As mentionedpreviously, it is imperative that the oven door 14 first be closed'andthen locked by moving the latch handle 86 to the third (locked)position. Also, it isimperative that the oven door remain closed andincapable of being opened while the oven temperatures are above normalcooking temperatures of about 580F. The door latch mechanism 50 is shownschematically in the circuit diagram of FIG. 8 by merely showing thereciprocating locking bar 127 with its two slots 155 and 157 incooperation with the autofunctioning of the microwave generator29, asseen in FIG. 1, it should suffice to say that these microwave circuitsare connected by the first interlock switch 60 across lines L, and LThis microwave interlock switch 60 is closed by positioning the latchhandle 86 in the second (locked) position of FIG. 3.

Modifications of this invention will occur to those skilled in this art,therefore, it is to be .understood that this invention is not limited tothe particular embodiments disclosed, but that it is intended to coverall modifications which are within the true spirit and scope of thisinvention as claimed.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is: b

l. A multiple position, sliding latch mechanism comprising a base, alatch handle pivotally connected to said base adjacent the rear thereof,a latch lever pivotally connected to the base and to the latch handle, alatching bolt pivotally connected to the base and joined to both thesaid latchlever and the base by a lost 'rnotion connection wherebymovement ofthe latch handle from a first (unlocked) position causes aturning action of the latch lever and hence a turning action of thelatching bolt, and indexing means associated with the latch lever totemporarilyhold thelatchmechanism in each of its multiple positions, anda locking bar pivotally connected tothe latch lever and'ex tendingrearwardly thereof, an-automatic lock'lever'associated with the lockingbar for locking the latch mechanism against further movement in theforward direction, and electroresponsive means for deactivating the locklever to enable the movement of the latch mechanism to-aft'hird positionat which point the automatic lock lever actsto lock the latch mechanismfrom further "movement, the said electroresponsive means again beingoperable to deactivate the said lock lever whereby the latch mechanismmay be shifted to any position.

2. A multiple position, sliding latch mechanism cornprising a baseplate, a latch handle pivotally connected to said base plate adjacentthe rear of the base plate, a latch lever pivotally connected to thebase plate and "to the latch handle, a latching bolt pivotallyconnectedto the base plate and pivotally and s'lidably connected'to the latchlever, whereby movement of the latch handle in one direction from afirst (unlockedlposi'tion to a second (locked) position'causes a turningaction ofthe latch lever in the opposite direction and also a turningaction of the latching bolt in the first direction u'n t'il it reachesthe second (locked) position, the latch handle having a third (locked)position which results in niovement of the latch lever without alteringthe locked" position of the locking bolt, and separate interlockingswitch means cooperating with the latch 'mechanis'r'n in each the secondand third positions to set upinde'pehdent control circuits.

3. A multiple position, sliding latchm'ech'anism asr'ecited in claim 2with indexing means associated with the latch lever to locate the secondand third locked positions of the latch handle.

4. A multiple position, sliding latch mechanism as recited in claim 3wherein the indexing means includes a cam surface formed on one sideedge of thelatch lever and a spring biased cam follower supported fromthe base plate for cooperation with the cam surface.

5. A multiple position, sliding latch mechanism-as recited in claim 4with a locking bar pivotallyconnec ted to the latch lever and extendingrearwardly thereof, an automatic lock lever associated with the lockingbar for locking the latch mechanism in the second (locked) positionagainst further movement in the forward direction, and anelectroresponsivemeans for deactivating the lock lever to enable themovement of the latch mechanism to the third (locked) position at whichpoint the automatic lock lever acts to hold the locking bar from furthermovement, the said electrorespon' si've means being operable todeactivate the said lock lever so that the latch mechanism may beshifted backto either its second or first positions.

6. A multiple position, sliding latch mechanism corn prising a baseplate, a latch lever pivotally connected I to the base plate, a latchingbolt pivotally connected to the base plate adjacent the front thereof,and a lost motion connection between the latching bolt and the latchlever, and an elongated latch handle having a lost motion connectionwith the base plate adjacent the rear thereof and overlying the latchmechanism and extend- 11 ing forwardly beyond the latching bolt in itsfully extended position, and a pivotal connection between the latchhandle and the latch lever whereby movement of the latch handle causes arelated movement of the latch lever and latching bolt for effecting alocking action, whereby the distal end ofthe latch handle moves in arelatively flat arc of a circle.

7. A multiple position, sliding latch mechanism as recited in claim 6wherein the said lost motion connection between the latching bolt andthelatch lever is extended whereby the latch handle has a first(unlocked) position, a second (locked) position and a third (locked)position, and indexing means associated with the said latch lever toestablish three distinct positions of the latch mechanism.

8. A multiple position, sliding latch mechanism as recited in claim 7with a locking bar pivotally connected to the latch lever and extendingrearwardlythereof, an automatic lock lever'associated with the lockingbar for locking the latch mechanism in the second (locked) positionagainst further movement in the forward direction, andanelectroresponsive means for deactivating thelock lever to enable'themovementof' the latch mechanism to the third (locked) position at whichposition the automatic lock lever acts to hold the latch mechanism fromfurther movement, the electroresponsive means being operable attemperatures below about 6 00F. in an associated control cavity todeactivate the automatic lock lever'so that the latch mechanism may beshifted to either its second (locked) position or the first (unlocked)position. v

9. A multipleposition, sliding latch mechanism as recited in claim 8with separate interlocking switch means cooperating with the latchmechanism in each the second and third positions to set up independentcontrol circuits. I

10. In a combined microwave and pyrolytic selfcleaning oven having anovencavity formed by a boxlike oven liner and a front-opening accessdoor, a multiple position, sliding latch mechanism mounted in the ovenbody adjacent the top front of the oven, said latch mechanism comprisinga base ,plate, a latch lever pivotally connected to the base plate, alatching bolt pivotally connected to the. base plate adjacent the frontthereof, and a lost'motion connection between the latching bolt and thelatch lever, and an elongated latch handle having a lost motionconnection with the base plate adjacent the rear thereof and overlyingthe latch mechanism and extending forwardly beyond the front surface ofthe oven door, and a pivotal connection between the latch handle and thelatch lever whereby movement of the latch handle causes a relatedmovement of the latch lever and latching bolt for effecting a lockingaction, whereby the distal end of the latch handle moves in a relativelyflat arc of a curve.

11. In a combined microwave and pyrolytic selfcleaning oven constructionas recited in claim 10, wherein the said lost motion connection betweenthe latching bolt and the latch lever is extended whereby the latchhandle has a first (unlocked) position, a second (locked) position and athird (locked) position, and separate interlocking switch meanscooperating with the latch mechanism in each the second and thirdpositions to set up independent control circuits for the oven.

l 12. ln a combined microwave and pyrolytic self- I vcleaning'ovenconstruction as recited in claim 11 with sponsive means for deactivatingthe lock lever to enable the movement of the latch mechanism to thethird (locked) position at which position the automatic lock lever actsto hold the latch mechanism from further movement, the electroresponsivemeans being operable at oven temperatures below about 600F. m deactivatethe automatic lock lever so that the latch mechanismmay be shifted toeither its second (locked) posi tion or the first (unlocked) position.

1. A multiple position, sliding latch mechanism comprising a base, alatch handle pivotally connected to said base adjacent the rear thereof,a latch lever pivotally connected to the base and to the latch handle, alatching bolt pivotally connected to the base and joined to both thesaid latch lever and the base by a lost motion connection wherebymovement of the latch handle from a first (unlocked) position causes aturning action of the latch lever and hence a turning action of thelatching bolt, and indexing means associated with the latch lever totemporarily hold the latch mechanism in each of its multiple positions,and a locking bar pivotally connected to the latch lever and extendingrearwardly thereof, an automatic lock lever associated with the lockingbar for locking the latch mechanism against further movement in theforward direction, and electroresponsive means for deactivating the locklever to enable the movement of the latch mechanism to a third positionat which point the automatic lock lever acts to lock the latch mechanismfrom further movement, the said electroresponsive means again beingoperable to deactivate the said lock lever whereby the latch mechanismmay be shifted to any position.
 2. A multiple position, sliding latchmechanism comprising a base plate, a latch handle pivotally connected tosaid base plate adjacent the rear of the base plate, a latch leverpivotally connected to the base plate and to the latch handle, alatching bolt pivotally connected to the base plate and pivotally andslidably connected to the latch lever, whereby movement of the latchhandle in one direction from a first (unlocked) position to a second(locked) position causes a turning action of the latch lever in theopposite direction and also a turning action of the latching bolt in thefirst direction until it reaches the second (locked) position, the latchhandle having a third (locked) position which results in movement of thelatch lever without altering the locked position of the locking bolt,and separate interlocking switch means cooperating with the latchmechanism in each the second and third positions to set up independentcontrol circuits.
 3. A multiple position, sliding latch mechanism asrecited in claim 2 with indexing means associated with the latch leverto locate the second and third locked positions of the latch handle. 4.A multiple position, sliding latch mechanism as recited in claim 3wherein the indexing means includes a cam surface formed on one sideedge of the latch lever and a spring biased cam follower supported fromthe base plate for cooperation with the cam surface.
 5. A multipleposition, sliding latch mechanism as recited in claim 4 with a lockingbar pivotally connected to the latch lever and extending rearwardlythereof, an automatic lock lever associated with the locking bar forlocking the latch mechanism in the second (locked) position againstfurther movement in the forward direction, and an electroresponsivemeans for deactivating the lock lever to enable the movement of thelatch mechanism to the third (locked) position at which point theautomatic lock lever acts to hold the locking bar from further movement,the said electroresponsive means being operable to deactivate the sAidlock lever so that the latch mechanism may be shifted back to either itssecond or first positions.
 6. A multiple position, sliding latchmechanism comprising a base plate, a latch lever pivotally connected tothe base plate, a latching bolt pivotally connected to the base plateadjacent the front thereof, and a lost motion connection between thelatching bolt and the latch lever, and an elongated latch handle havinga lost motion connection with the base plate adjacent the rear thereofand overlying the latch mechanism and extending forwardly beyond thelatching bolt in its fully extended position, and a pivotal connectionbetween the latch handle and the latch lever whereby movement of thelatch handle causes a related movement of the latch lever and latchingbolt for effecting a locking action, whereby the distal end of the latchhandle moves in a relatively flat arc of a circle.
 7. A multipleposition, sliding latch mechanism as recited in claim 6 wherein the saidlost motion connection between the latching bolt and the latch lever isextended whereby the latch handle has a first (unlocked) position, asecond (locked) position and a third (locked) position, and indexingmeans associated with the said latch lever to establish three distinctpositions of the latch mechanism.
 8. A multiple position, sliding latchmechanism as recited in claim 7 with a locking bar pivotally connectedto the latch lever and extending rearwardly thereof, an automatic locklever associated with the locking bar for locking the latch mechanism inthe second (locked) position against further movement in the forwarddirection, and an electroresponsive means for deactivating the locklever to enable the movement of the latch mechanism to the third(locked) position at which position the automatic lock lever acts tohold the latch mechanism from further movement, the electroresponsivemeans being operable at temperatures below about 600*F. in an associatedcontrol cavity to deactivate the automatic lock lever so that the latchmechanism may be shifted to either its second (locked) position or thefirst (unlocked) position.
 9. A multiple position, sliding latchmechanism as recited in claim 8 with separate interlocking switch meanscooperating with the latch mechanism in each the second and thirdpositions to set up independent control circuits.
 10. In a combinedmicrowave and pyrolytic self-cleaning oven having an oven cavity formedby a box-like oven liner and a front-opening access door, a multipleposition, sliding latch mechanism mounted in the oven body adjacent thetop front of the oven, said latch mechanism comprising a base plate, alatch lever pivotally connected to the base plate, a latching boltpivotally connected to the base plate adjacent the front thereof, and alost motion connection between the latching bolt and the latch lever,and an elongated latch handle having a lost motion connection with thebase plate adjacent the rear thereof and overlying the latch mechanismand extending forwardly beyond the front surface of the oven door, and apivotal connection between the latch handle and the latch lever wherebymovement of the latch handle causes a related movement of the latchlever and latching bolt for effecting a locking action, whereby thedistal end of the latch handle moves in a relatively flat arc of acurve.
 11. In a combined microwave and pyrolytic self-cleaning ovenconstruction as recited in claim 10, wherein the said lost motionconnection between the latching bolt and the latch lever is extendedwhereby the latch handle has a first (unlocked) position, a second(locked) position and a third (locked) position, and separateinterlocking switch means cooperating with the latch mechanism in eachthe second and third positions to set up independent control circuitsfor the oven.
 12. In a combined microwave and pyrolytic self-cleaningoven construction as recited in claim 11 with indexing means associatedwith the said latch lever to establish threE distinct positions of thelatch mechanism.
 13. In a combined microwave and pyrolytic self-cleaningoven construction as recited in claim 12, with a locking bar pivotallyconnected to the latch lever and extending rearwardly thereof, anautomatic lock lever associated with the locking bar for locking thelatch mechanism in the second (locked) position against further movementin the forward direction, an electroresponsive means for deactivatingthe lock lever to enable the movement of the latch mechanism to thethird (locked) position at which position the automatic lock lever actsto hold the latch mechanism from further movement, the electroresponsivemeans being operable at oven temperatures below about 600*F. todeactivate the automatic lock lever so that the latch mechanism may beshifted to either its second (locked) position or the first (unlocked)position.